The Spatio-temporal Heterogenity Research Of Thermal Environment In 2000-2014 Winter And Summer,in Beijing Area

Not only the rapid development of urbanization bring high economic growth,but also increases pollution,energy consumption,climate warming,the deterioration of urban ecological environment quality and so on a series of problems.As a key factor affecting the quality of urban ecological environment,the change of the urban heat island effect is increasingly becoming the focus of residents.The spatio-temporal heterogenity of the thermal environment is the basis of the study of urban thermal environment.The study of its spatio-temporal heterogenity and influence mechanisms is of great significance to improve the urban ecological environment and the quality of urban human settlement environment,remission the urban heat island effect.The area within six rings of Beijing as a typical rapid urbanization city in China has been taken as an example in this study.We uses the remote sensing data of MODIS and Landsat to study seasonal variation and spatio-temporal heterogenity of the urban thermal environment based on region,landscape and patch three scales.The urban heat island index is used to study the seasonal variation of the urban thermal environment in regional scale.The paper analyzes the spatio-temporal heterogenity during 2000 to 2014 by the method of temperature normalization and landscape spatial centroid analysis.The spatial pattern characteristics of urban thermal landscape are studied by landscape pattern index and spatial autocorrelation analysis.From morphological characteristics angle,based on the mathematical morphological spatial pattern analysis(MSPA)method to extract the summer high temperature patches and low temperature patches,analysising its time-space distribution features.Using the data of land utilization to discuss the influence mechanism of long-term high temperature patches and low temperature patches from the perspective of landscape heterogeneity.The results show that:(1)The urban heat island effect is shown in the area within six rings of Beijing in summer,the cold island effect in winter.The temperature of the study area increases,urban heat island effect is enhanced in summer,urban cold island effect is weakened in winter.(2)In summer,the temperature of the area within the four rings of Beijing is higher than the area outside the four rings.The area of medium temperature is increasing,the area of high temperature,sub-high temperature and cooling temperature is decreasing.The aggregation degree of the heat island patches decreases and the patches distribution are more fragmented,especially the very high temperature patches.In winter,the temperature of the area within the three rings of Beijing is lower than the area outside the three rings.The area of the secondary medium temperature and middle temperature is increasing and the area of the cooling temperature is increasing slowly.The distribution of the high temperature patches gradually concentrated,cooling temperature patches distribute gradually scattered.(3)In summer,the long-term high temperature patches are mainly distributed in the southwest of Daxing District,Fengtai District,Shijingshan District,Chaoyang District,Changping District and Shunyi District.The long-term low temperature patches are mainly distributed in the junction of Shijingshan District,Mentougou and Haidian District and the southeast of Changping District.The influencing factors of high temperature patches spatial temporal distribution characteristics are: the surface condition of the vegetation cover,population density and human socioeconomic activities.The influencing factors of low temperature patches spatial temporal distribution characteristics are water,vegetation and landscape structure.